21220111100 has 72 divisors (see below), whose sum is σ = 47068393680. Its totient is φ = 8301368320.

The previous prime is 21220111067. The next prime is 21220111109. The reversal of 21220111100 is 111102212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220111109) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1153172 + ... + 1171428.

It is an arithmetic number, because the mean of its divisors is an integer number (653727690).

Almost surely, 2^21220111100 is an apocalyptic number.

21220111100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21220111100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23534196840).

21220111100 is an abundant number, since it is smaller than the sum of its proper divisors (25848282580).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21220111100 is a wasteful number, since it uses less digits than its factorization.

21220111100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18527 (or 18520 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21220111100 its reverse (111102212), we get a palindrome (21331213312).

The spelling of 21220111100 in words is "twenty-one billion, two hundred twenty million, one hundred eleven thousand, one hundred".